The taxonomic position of two species of the genus Klebsiella (K. atlantae and K. edwardsii) is being introduced. 211 strains of different origin were studied: 80 strains of K. pneumoniae, 46 strains of K. oxytoca, 50 strains of K. atlantae and 35 strains of K. edwardsii. Sixty biochemical characteristics were determined 40 of these pertaining to carbohydrate metabolism. It was discussed whether both are to be considered species or biotypes of another Klebsiella species, however, by determining citrate as carbon source, by MR test and by tests on malonate, gluconate, methyl-xyloside, 1 (--) sorbose, inulin, amylose, methyl-d-mannoside, glycogen, melezitose, VP test, amygdalin, d-tartrate and gas from glucose, we arrived at the conclusion that both could be considered species of the genus. These conclusions were confirmed by the determination of biotypes of both (according to C. Richard). Later, we expect to study their participation in human infective processes and their sensitivity by antibiotic therapy.